This invention relates generally to a method of and apparatus for cutting sheet material and, in particular, to a method of and apparatus for precisely scoring a portion of a laminar imaging media in order to create a tab for facilitating media delamination.
Laminar imaging media, such as thermographic print media are used in the formation of images. Thermographic materials have images formed thereon in response to laser energy being applied thereto. This print media is a relatively thin laminate comprising essentially a substrate, an overlying disposable peelable sheet, and an intermediate multicomponent image forming layer including adhesives joining the substrate and peel sheet. After the application of laser energy for forming an image on the media, the peel sheet is peeled relative to the substrate for effecting a desired delamination. As a consequence of such peeling, the desired image remains on the substrate. Until peeling, however, it is important that the laminate remain intact. Because of the requirement that the media be peeled and because the material is relatively difficult to handle for a number of reasons, the substrate is formed with a frangible tab portion formed along a score line adjacent a marginal edge of the media. The tab portion is designed to break or snap along the score line upon the application of forces thereto in order to initiate such separation of the peel sheet from the substrate. The thermographic film is normally provided with such a tab in its fabrication process. However for some imaging applications, it is desirable that the film not be imaged with a tab portion. Therefore, there is a requirement that a tab portion for facilitating delamination be formed following the imaging step. Scoring of the sheet material is common practice and typically involves use of a cutting implement which traverses the material, for example along a marginal edge of sheet material. Some of the scoring or cutting techniques include the controlled penetration of a layer of a laminate.
Exemplary of known scoring or cutting apparatus of the last noted type are described in the following U.S. Pat. Nos.: 3,165,951; 3,909,582; 4,516,461; 4,517,872; 4,519,285; and, 5,220,858. However, there is a continuing desire to improve on apparatus and methods for reliably and simply scoring imaging media in a manner which insures a controlled depth of cut regardless of thickness variations of imaging media sheet, and in a manner which does not damage the imaging media being handled.